PostgreSQL High Availability Cookbook - Second Edition

How to do it...

For this, we will assume pg1 is our current primary node and VG_POSTGRES/LV_DATA is the principal data volume. Follow these steps as the root user to create and use an LVM snapshot:

1. Create the snapshot with lvcreate:

        lvcreate -l 100%FREE -s -n snap VG_POSTGRES/LV_DATA

2. Create a directory on which to mount the snapshot using this command:

        mkdir /mnt/db_snap

3. Mount the snapshot as a regular XFS filesystem using this command:

        mount -t xfs -o nouuid /dev/VG_POSTGRES/snap /mnt/db_snap

4. Enter the snapshot pgdata directory using this command:

        cd /mnt/db_snap/pgdata

5. Examine snapshot information with lvdisplay:

        lvdisplay VG_POSTGRES/snap | grep snap

 

Follow these steps as the root user to unmount and remove an LVM ...